Boost leak test question. - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

unicoder · 02-01-2018, 01:40 PM

So I did a boost leak test on my KA-T S14 today.

Had your typical "clamp too loose" leaks and was able to fix those just fine, but I could hear a whooshing sound from like under the intake manifold.

My questions:
- Since it's after the TB, would that be unmetered air just coming from the crankcase? I confirmed the egr block off wasn't the source of the air.
- What's possibly leaking?
- I heard a creaking sound while pressurizing and of course now there is oil on the ground, likely blew out the back of my valve cover gasket maybe?

Just looking for some tips of where to look next. Oil pan looks fine, but haven't been able to get under her yet.

RomulanS13 · 02-01-2018, 02:26 PM

I heard the same sound come from mine but after a few tries of crank no start. And it was coming from the idle air control valve.

Sent from my SM-G950U using Tapatalk

unicoder · 02-01-2018, 02:34 PM

I can totally take a look at that! Would that blow oil out as well? or was that just likely my valve cover gasket leak getting worse from the pressure

RomulanS13 · 02-01-2018, 04:02 PM

Quote:

Originally Posted by unicoder

I can totally take a look at that! Would that blow oil out as well? or was that just likely my valve cover gasket leak getting worse from the pressure

No there should not be any oil coming from there.

Sent from my SM-G950U using Tapatalk

EnnEssEnnKAT · 02-01-2018, 05:33 PM

There's 4 rubber hoses on the underside of the stock intake manifold that combine onto one hose that goes to the pcv. Not sure what you did about that but those rubber hoses have been known to blow off and or crack once going boosted.

Sent from mTalk

KAT-PWR · 02-01-2018, 08:31 PM

How do you have the PCV set up? Still ran to the intake manifold? All of that needs to be removed aside from the PCV box on the timing cover which should be ran to a vented catch can.

If you're having air coming out from the boost leak test via the valve cover or PCV you have a tired engine with very poor ring seal.

Quote:

Originally Posted by EnnEssEnnKAT

There's 4 rubber hoses on the underside of the stock intake manifold that combine onto one hose that goes to the pcv. Not sure what you did about that but those rubber hoses have been known to blow off and or crack once going boosted.

Sent from mTalk

None of the factory PCV tree should be left EVER when boosting.

Remove the manifold, knock out the PCV ports from the runners, tap and plug or weld them shut.
Run the PCV on the timing cover to a vented catch can.

*anti tyler* · 02-01-2018, 10:57 PM

It's probably coming from one of the headless hex plugs in your intake runner.

I had the one in the rear leak air like a bitch. Look up some pictures of the intake to know what I mean.

unicoder · 02-03-2018, 07:21 PM

Quote:

Originally Posted by KAT-PWR

How do you have the PCV set up? Still ran to the intake manifold? All of that needs to be removed aside from the PCV box on the timing cover which should be ran to a vented catch can.

If you're having air coming out from the boost leak test via the valve cover or PCV you have a tired engine with very poor ring seal.

None of the factory PCV tree should be left EVER when boosting.

Remove the manifold, knock out the PCV ports from the runners, tap and plug or weld them shut.
Run the PCV on the timing cover to a vented catch can.

Got it! Thanks a lot!

Car drives fine, runs and pulls strong. 148k on the odo, and 160psi across all 4 cylinders. I am only chasing the sound now. Just a big woosh from the passenger side, not sure where it's coming from. But after charging it and hearing the stretching/crackling sound, im getting oil on the ground, which may be from the PCV - i am going to get all of that removed now.

Hoffman5982 · 02-07-2018, 10:45 PM

It could also be the gasket between the runners and the plenum....surprised that wasn't the very first suggestion. When I boost leak tested mine it was leaking there

unicoder · 02-08-2018, 12:36 PM

Quote:

Originally Posted by Hoffman5982

It could also be the gasket between the runners and the plenum....surprised that wasn't the very first suggestion. When I boost leak tested mine it was leaking there

Thanks! I’m going to test again and focus on that

unicoder · 02-09-2018, 09:43 PM

I removed the intake manifold today, and yes there were tons of dryrotted hoses. I am going to remove all of them and the PCV system.

However, still don't know where all the oil is coming from, gonna be fun.,

unicoder · 02-12-2018, 03:00 PM

Well, got me a 3/8-16 tap and some plugs from Tractor Supply Co. Fit like a dream. May JB Weld them in there since threadlocker hasn't been my best friend on this engine

*TheRealSy90* · 02-12-2018, 04:06 PM

It's possible you pressurized the crank case and blew the rear main seal out. I've seen this happen on cars with incorrectly routed catch cans that were putting boost into the crank case.

unicoder · 02-12-2018, 05:02 PM

Once i get this intake back on, I will be doing a thorough clean and search for source of the leak. I think it could be either my front timing cover seal, or the turbo drain tube may have damage to it. But I will know more soon!

*TheRealSy90* · 02-12-2018, 06:12 PM

If you haven't ran the engine this whole time I think it would be weird to still have oil present around the timing cover or valve cover gasket.

unicoder · 02-20-2018, 04:52 PM

Got her all finished up and drove it home today. No more sputtering! The boost leak was definitely in either the plenum gasket or the PCV system.

Thanks guys!!! It's perfect!

02-01-2018, 01:40 PM	#1
unicoder Zilvia Member Join Date: Apr 2017 Location: Alabama Posts: 160 Trader Rating: (2) Feedback Score: 2 reviews	Boost leak test question. So I did a boost leak test on my KA-T S14 today. Had your typical "clamp too loose" leaks and was able to fix those just fine, but I could hear a whooshing sound from like under the intake manifold. My questions: - Since it's after the TB, would that be unmetered air just coming from the crankcase? I confirmed the egr block off wasn't the source of the air. - What's possibly leaking? - I heard a creaking sound while pressurizing and of course now there is oil on the ground, likely blew out the back of my valve cover gasket maybe? Just looking for some tips of where to look next. Oil pan looks fine, but haven't been able to get under her yet. __________________ 5.3 V8 Swap w/ Nitrous

02-01-2018, 02:34 PM	#3
unicoder Zilvia Member Join Date: Apr 2017 Location: Alabama Posts: 160 Trader Rating: (2) Feedback Score: 2 reviews	I can totally take a look at that! Would that blow oil out as well? or was that just likely my valve cover gasket leak getting worse from the pressure __________________ 5.3 V8 Swap w/ Nitrous

02-07-2018, 10:45 PM	#9
Hoffman5982 Nissanaholic! Join Date: Jan 2009 Location: Definitely NOT FL.... Age: 29 Posts: 2,491 Trader Rating: (25) Feedback Score: 25 reviews	It could also be the gasket between the runners and the plenum....surprised that wasn't the very first suggestion. When I boost leak tested mine it was leaking there __________________

02-09-2018, 09:43 PM	#11
unicoder Zilvia Member Join Date: Apr 2017 Location: Alabama Posts: 160 Trader Rating: (2) Feedback Score: 2 reviews	I removed the intake manifold today, and yes there were tons of dryrotted hoses. I am going to remove all of them and the PCV system. However, still don't know where all the oil is coming from, gonna be fun., __________________ 5.3 V8 Swap w/ Nitrous

02-12-2018, 03:00 PM	#12
unicoder Zilvia Member Join Date: Apr 2017 Location: Alabama Posts: 160 Trader Rating: (2) Feedback Score: 2 reviews	Well, got me a 3/8-16 tap and some plugs from Tractor Supply Co. Fit like a dream. May JB Weld them in there since threadlocker hasn't been my best friend on this engine __________________ 5.3 V8 Swap w/ Nitrous

02-01-2018, 02:26 PM	#2
RomulanS13 Join Date: Oct 2017 Location: near salty oceans Posts: 30 Trader Rating: (0) Feedback Score: 0 reviews	I heard the same sound come from mine but after a few tries of crank no start. And it was coming from the idle air control valve. Sent from my SM-G950U using Tapatalk

02-01-2018, 05:33 PM	#5
EnnEssEnnKAT Zilvia Junkie Join Date: Sep 2014 Location: New Hampshire Posts: 427 Trader Rating: (13) Feedback Score: 13 reviews	There's 4 rubber hoses on the underside of the stock intake manifold that combine onto one hose that goes to the pcv. Not sure what you did about that but those rubber hoses have been known to blow off and or crack once going boosted. Sent from mTalk

02-12-2018, 05:02 PM	#14
unicoder Zilvia Member Join Date: Apr 2017 Location: Alabama Posts: 160 Trader Rating: (2) Feedback Score: 2 reviews	Once i get this intake back on, I will be doing a thorough clean and search for source of the leak. I think it could be either my front timing cover seal, or the turbo drain tube may have damage to it. But I will know more soon! __________________ 5.3 V8 Swap w/ Nitrous

02-20-2018, 04:52 PM	#16
unicoder Zilvia Member Join Date: Apr 2017 Location: Alabama Posts: 160 Trader Rating: (2) Feedback Score: 2 reviews	Got her all finished up and drove it home today. No more sputtering! The boost leak was definitely in either the plenum gasket or the PCV system. Thanks guys!!! It's perfect! __________________ 5.3 V8 Swap w/ Nitrous

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode